1. Field of the Invention
The present invention relates to a method of detecting dissolve/fade in an MPEG-compressed video environment, and more particularly, to a method of detecting a dissolve/fade sequence using spatio-temporal macro block type distribution in a compressed video environment, to effectively detect dissolve/fade in video streams.
2. Description of the Related Art
To watch a desired video (moving picture such as movie, drama, news, documentary, etc.) through TV and video media, a user should watch the entire program at a fixed televising time. With the development in digital technology and image/video recognition techniques in recent years, however, users can search and browse a desired part of a desired video at a desired time. A basic technique for non-linear browsing and searching includes a shot segmentation and a shot clustering. A variety of studies are being performed for the shot segmentation technique while researches with respect to the shot clustering technique are at the initial stage.
A shot is a sequence of video frames obtained by one camera without interruption. The shot is a basic unit for analyzing or constructing a video content. Video is generally configured of a connection of lots of shots and various video editing effects are used according to methods of connecting the shots. The video editing effects include an abrupt shot transition and a gradual shot transition. The abrupt shot transition is a technique whereby the current picture is abruptly changed into another picture. This abrupt shot transition is also called hard cut and prevalently used. The gradual shot transition is a technique whereby a picture is gradually changed into another picture. The gradual shot transition includes fade, dissolve, wipe and other special effects. Among these, the fade and dissolve are most frequently used.
Shot segmentation represents a process of extracting temporal information, such as frame numbers, of each shot of a video based on the transition detection.
There are many shot transition detection algorithms that can be categorized as three conventional methods for detecting the gradual shot transition. The first one is a twin comparison technique based on a color histogram difference between frames. This technique has erroneous detection and non-detection and slower performance speed because it is based on only the global color histogram difference between frames. The second method is a dissolve/fade detection technique based on the variance of global brightness distribution of frames. This technique uses brightness variation characteristic in I-frames and P-frames of a fade/dissolve sequence including a brightness variance graph that has a parabolic form and very large difference between the maximum and minimum values and the editing effect of dissolve or fade lasts over several to tens frames. However, the brightness variance distribution uses a basis for detecting the dissolve/fade effect in this method frequently appears even in a sequence where dissolve/fade is not generated. Moreover, the brightness variance distribution may not arise in the sequence where the dissolve/fade is generated in many cases.
The third method is a dissolve/fade detecting technique based on edge distribution in an image according to an edge detection algorithm and analysis of moving picture characteristic of the detected edge. This method passes through a preprocessing step of detecting edges from image data, a step of dividing the detected edges into entering edges and exiting edges using the moving picture characteristic and calculating an edge variation rate on the basis of the divided edges, and a post-processing step of classifying editing effects using spatio-temporal distribution of the entering edges and exiting edges, to detect the editing effects of hard cut, dissolve, fade and wipe. However, this method has very a slow performance speed because most images must be actually decoded basically and the edge detection operation requires relatively long period of time.